The present invention relates generally to use of recombinant viruses as vectors, and more specifically, to recombinant alphaviruses which are capable of expressing a heterologous sequence in target cells.
Alphaviruses comprise a set of serologically related arthropod-borne viruses of the Togavirus family. Briefly, alphaviruses are distributed worldwide, and persist in nature through a mosquito to vertebrate cycle. Birds, rodents, horses, primates, and humans are among the defined alphavirus vertebrate reservoir/hosts.
Twenty-six known viruses and virus subtypes have been classified within the alphavirus genus utilizing the hemagglutination inhibition (HI) assay. Briefly, the HI test segregates the 26 alphaviruses into three major complexes: the Venezuelan encephalitis (VE) complex, the Semliki Forest (SF) complex, and the western encephalitis (WE) complex. In addition, four additional viruses, eastern encephalitis (EE), Barmah Forest, Middleburg, and Ndumu, receive individual classification based on the HI serological assay.
Members of the alphavirus genus are also classified based on their relative clinical features in humans: alphaviruses associated primarily with encephalitis, and alphaviruses associated primarily with fever, rash, and polyarthritis. Included in the former group are the VE and WE complexes, and EE. In general, infection with this group can result in permanent sequelae, including behavior changes and learning disabilities, or death. In the latter group is the SF complex, comprised of the individual alphaviruses Chikungunya, O""nyong-nyong, Sindbis, Ross River, and Mayaro. With respect to this group, although serious epidemics have been reported, infection is in general self-limiting, without permanent sequelae.
Sindbis virus is the prototype member of the alphavirus genus of the Togavirus family. Although not usually apparent, clinical manifestations of Sindbis virus infection may include fever, arthritis, and rash. Sindbis virus is distributed over Europe, Africa, Asia, and Australia, with the best epidemiological data coming from South Africa, where 20% of the population is seropositive. (For a review, see Peters and Dalrymple, Fields Virology (2nd ed), Fields et al. (eds.), B.N. Raven Press, New York, N.Y., chapter 26, pp. 713-762). Infectious Sindbis virus has been isolated from human serum only during an outbreak in Uganda and in a single case from Central Africa.
The morphology and morphogenesis of the alphavirus genus is generally quite uniform. In particular, the enveloped 60-65 nm particles infect most vertebrate cells, where productive infection is cytopathic. On the other hand, infection of invertebrate cells, for example, those derived from mosquitoes, does not result in any overt cytopathology. Typically, alphaviruses are propagated in BHK-21 or vero cells, where growth is rapid, reaching a maximum yield within 24 hours of infection. Field strains are usually isolated on primary avian embryo, for example chicken fibroblast cultures (CEF).
The genomic RNA (49S RNA) of alphaviruses is unsegmented, of positive polarity, approximately 11-12 kb in length, and contains a 5xe2x80x2 cap and a 3xe2x80x2 polyadenylate tail. Infectious enveloped virus is produced by assembly of the viral nucleocapsid proteins onto genomic RNA in the cytoplasm, and budding through the cell membrane embedded with viral-encoded glycoproteins. Entry of virus into cells appears to occur by endocytosis through caltherin-coated pits, fusion of the viral membrane with the endosome, release of the nucleocapsid and uncoating of the viral genome. During viral replication, the genomic 49S RNA serves as template for synthesis of a complementary negative strand. The negative strand in turn serves as template for full-length genomic RNA and for an internally initiated positive-strand 26S subgenomic RNA. The nonstructural proteins are translated from the genomic RNA. Alphaviral structural proteins are translated from the subgenomic 26S RNA. All viral genes are expressed as polyproteins and processed into individual proteins by proteolytic cleavage post-translation.
The use of recombinant virus vectors (in particular, alphavirus vectors) to treat individuals requires that they be able to be transported and stored for long periods at a desired temperature, such that infectivity and viability of the recombinant virus is retained. Current methods for storing recombinant viruses generally involve storage as liquids and at low temperatures. Such methods present problems in Third World countries, which typically do not have adequate refrigeration capabilities. For example, each year in Africa, millions of children die from infectious diseases such as measles. Vaccines necessary for the prevention of these diseases cannot be distributed to the majority of these countries because refrigeration is not readily accessible.
In addition to storage as liquids and at low temperatures, present viral formulations often contain media components that are not desirable for injection into patients. Consequently, there is a need in the art for a method of preserving purified recombinant viral vector (and in particular, alphavirus vectors) in a lyophilized form at elevated temperatures, and for this form to be suitable for injection into patients.
The present invention discloses recombinant alphavirus vectors which are suitable for use in a variety of applications, including for example, gene therapy, and further provides other related advantages.
Briefly sated, the present invention provides alphavirus vector constructs and alphavirus particles, as well as methods of making and utilizing the same. Within one aspect of the present invention, alphavirus vector constructs are provided comprising a 5xe2x80x2 promoter which is capable of initiating the synthesis of viral RNA in vitro from cDNA, a 5xe2x80x2 sequence which is capable of initiating transcription of an alphavirus, a nucleotide sequence encoding alphavirus non-structural proteins, a viral junction region which has been inactivated such that the viral transcription of the subgenomic fragment is prevented, and an alphavirus RNA polymerase recognition sequence. Within other aspects of the present invention, the viral junction region has been modified such that viral transcription of the subgenomic fragment is reduced.
Within yet other aspects of the present invention, alphavirus vector constructs are provided comprising a 5xe2x80x2 promoter which is capable of initiating the synthesis of viral RNA in vitro from cDNA, a 5xe2x80x2 sequence which is capable of initiating transcription of an alphavirus, a nucleotide sequence encoding alphavirus non-structural proteins, a first viral junction region which has been inactivated such that viral transcription of the subgenomic fragment is prevented, a second viral junction region which is active, or which has been modified such that viral transcription of the subgenomic fragment is reduced, and an alphavirus RNA polymerase recognition sequence.
Within still other aspects of the present invention, alphavirus cDNA vector constructs are provided, comprising a 5xe2x80x2 promoter which is capable of initiating the synthesis of viral RNA from cDNA, followed by a 5xe2x80x2 sequence which is capable of initiating transcription of an alphavirus, a nucleotide sequence encoding alphavirus non--structural proteins, a viral junction region which has been inactivated such that viral transcription of the subgenomic fragment is prevented, an alphavirus RNA polymerase recognition sequence, and a 3xe2x80x2 sequence which controls transcription termination.
Within another aspect of the present invention, alphavirus cDNA vector constructs are provided, comprising a 5xe2x80x2 promoter which is capable of initiating the synthesis of viral RNA from cDNA, followed by a 5xe2x80x2 sequence which is capable of initiating transcription of an alphavirus, a nucleotide sequence encoding alphavirus non-structural proteins, a viral junction region which is active, or which has been modified such that viral transcription of the subgenomic fragment is reduced, an alphavirus RNA polymerase recognition sequence, and a 3xe2x80x2 sequence which controls transcription termination.
Within another aspect of the present invention, alphavirus cDNA vector constructs are provided, comprising a promoter which is capable of initiating the synthesis of viral RNA from cDNA followed by a 5xe2x80x2 sequence which is capable of initiating transcription of an alphavirus, a nucleotide sequence encoding alphavirus non-structural proteins, a first viral junction region which has been inactivated such that viral transcription of the subgenomic fragment is prevented, followed by a second viral junction region which is active, or which has been modified such that viral transcription of the subgenomic fragment is reduced, an alphavirus RNA polymerase recognition sequence, and a 3xe2x80x2 sequence which controls transcription termination.
Within other aspects of the present invention, eukaryotic layered vector initiation systems are provided which are capable of expressing a heterologous nucleic acid sequence in a eukaryotic cell transformed or transfected therewith. In particular embodiments, eukaryotic layered vector initiation systems are provided, comprising a promoter which is capable of initiating the 5xe2x80x2 synthesis of RNA from cDNA, a vector construct which is capable of autonomous replication in a cell, the vector construct being capable of expressing a heterologous nucleic acid sequence, and a 3xe2x80x2 sequence which controls transcription termination.
Within a related aspect, eukaryotic layered vector initiation systems are provided, comprising a DNA promoter which is capable of initiating the 5xe2x80x2 synthesis of RNA from cDNA, a vector construct which is capable of autonomous replication in a cell, the vector construct being capable of expressing a heterologous ribonucleic acid sequence, and a 3xe2x80x2 DNA sequence which controls transcription termination.
Within one embodiment, the vector construct within the eukaryotic layered vector initiation systems of the present invention is an alphavirus vector construct. Within other embodiments, the construct is derived from a virus selected from the group consisting of poliovirus, rhinovirus, coxsackieviruses, rubella, yellow fever, HCV, TGEV, IBV, MHV, BCV, parainfluenza virus, mumps virus, measles virus, respiratory syncytial virus, influenza virus, RSV, MoMLV, HIV, HTLV, hepatitis delta virus and Astrovirus. Within yet other embodiments, the promoter which is capable of initiating the 5xe2x80x2 synthesis of RNA from cDNA is selected from the group consisting of the MoMLV promoter, metallothionein promoter, glucocorticoid promoter, SV 40 promoter, and the CMV promoter. Within further embodiments, the eukaryotic layered vector initiation systems further comprise a polyadenylation sequence.
In further embodiments of the invention, in any of the above aspects, the vectors (e.g., alphavirus vector construct, alphavirus cDNA vector construct, or eukaryotic layered vector initiation system) may be derived from an alphavirus selected from the group consisting of Aura, Fort Morgan, Venezuelan Equine Encephalitis, Ross River, Semliki Forest, Sindbis, and Mayaro.
In other embodiments, the vectors described above contain a heterologous sequence. Typically, such vectors contain a heterologous nucleotide sequence of greater than 100 bases, generally the heterologous nucleotide sequence is greater than 3 kb, and sometimes greater than 5 kb, or even 8 kb. In various embodiments, the heterologous sequence is a sequence encoding a protein selected from the group consisting of IL-1, IL-2, IL-3, IL-4, IL-5, IL-6, IL-7, IL-8, IL-9, IL-10, IL-11, IL-12, IL-13, IL-14, IL-15,alpha-, beta-, or gamma-IFN, G-CSF, and GM-CSF. Within other embodiments of the invention, the heterologous sequence may encode a lymphokine receptor. Representative examples of such receptors include receptors for any of the lymphokines set forth above.
In still other embodiments, the vectors described above include a selected heterologous sequence which may be obtained from a virus selected from the group consisting of influenza virus, HPV, HBV, HCV, EBV, HIV, HSV, FeLV, FIV, Hanta virus, HTLV I, HTLV II and CMV. Within one preferred embodiment, the heterologous sequence obtained from HPV encodes a protein selected from the group consisting of E5,E6, E7 and L1. In yet other embodiments, the vectors described above include a selected heterologous sequence encoding an HIV protein selected from the group consisting of HIV gp120 and gag.
The selected heterologous sequences described above also may be an antisense sequence, noncoding sense sequence, or ribozyme sequence. In preferred embodiments, the antisense or noncoding sense sequence is selected from the group consisting of sequences which are complementary to influenza virus, HPV, HBV, HCV, EBV, HIV, HSV, FeLV, FIV, Hanta virus, HTLV I, HTLV II, and CMV sequences.
In another embodiment, the vectors described above contain no alphavirus structural protein genes. Within other embodiments, the selected heterologous sequence is located downstream from a viral junction region. In the vectors described above having a second viral junction, the selected heterologous sequence may, within certain embodiments, be located downstream from the second viral junction region. Where the heterologous sequence is located downstream from a viral junction region, the vector construct may further comprise a polylinker located subsequent to the viral junction region. Within preferred embodiments, such polylinkers do not contain a restriction endonuclease recognition sequence present in the wild-type alphavirus sequence.
In yet another embodiment, in the vectors described above the selected heterologous sequence may be located within the nucleotide sequence encoding alphavirus non-structural proteins.
In particular embodiments, the vectors described above include a viral junction region consisting of the nucleotide sequence as shown in FIG. 3, from nucleotide number 7579, to nucleotide number 7597 (SEQ. ID NO. 1). In alternative embodiments, where the vector includes a second viral junction, an E3 adenovirus gene may be located downstream from the second viral junction region. Vectors of the present invention may also further comprise a non-alphavirus (for example retrovirus, coronavirus, hepatitis B virus) packaging sequence located between the first viral junction region and the second viral junction region, or in the nonstructural protein coding region.
In further aspects, the present invention provides an isolated recombinant alphavirus vector which does not contain a functional viral junction region, and which in preferred embodiments produces reduced viral transcription of the subgenomic fragment.
In still a further aspect, the present invention provides an alphavirus structural protein expression cassette, comprising a promoter and one or more alphavirus structural protein genes, the promoter being capable of directing the expression of alphavirus structural proteins. In various embodiments, the expression cassette is capable of expressing alphavirus structural proteins, such as an alphavirus structural protein selected from the group consisting of C, 6K, E3, E2, and E1.
Within other embodiments, the alphavirus structural protein is derived from an alphavirus selected from the group consisting of Aura, Fort Morgan, Venezuelan Equine Encephalitis, Ross River, Semliki Forest, Sindbis and Mayaro viruses.
In yet another aspect, the present invention provides an alphavirus structural protein expression cassette, comprising a promoter, one or more alphavirus structural proteins, and a heterologous ligand sequence, the promoter being capable of directing the expression of the alphavirus structural proteins and the heterologous sequence. In various embodiments, the heterologous ligand sequence is selected from the group consisting of VSVG, HIV gp120, antibody, insulin, and CD4.
In certain embodiments, the expression cassettes described above include a promoter selected from the group consisting of metallothionein, Drosophila actin 5C distal, SV40, heat shock protein 65, heat shock protein 70, Py, RSV, BK, JC, MuLV, MMTV, alphavirus junction region CMV and VA1RNA.
The present invention also provides packaging cell lines and producer cell lines suitable for producing recombinant alphavirus particles. Such packaging or producer cell lines may be either mammalian or non-mammalian (e.g., insect cells, such as mosquito cells). In certain embodiments, the packaging cell lines and producer cell lines contain an integrated alphavirus structural protein expression cassette.
Within one embodiment, packaging cell lines are provided which, upon introduction of a vector construct, produce alphavirus particles capable of infecting human cells. Within other embodiments, the packaging cell line produces alphavirus particles in response to one or more factors. Within certain embodiments, an alphavirus inhibitory protein is not produced within the packaging cell line.
Within other aspects, retroviral-derived packaging cell lines are provided which are suitable for packaging and production of an alphavirus vector. Within one embodiment, a retroviral-derived producer cell line suitable for packaging and production of an alphavirus vector is provided, comprising an expression cassette which directs the expression of gag/pol, an expression cassette which directs the expression of env, and alphavirus vector construct containing a retroviral packaging sequence.
Within another aspect, HBV-derived and coronavirus-derived packaging cell lines are provided which are suitable for packaging and production of and alphavirus vector. Within one embodiment, an HBV-derived packaging cell line is provided, comprising an expression cassette which directs the expression of HBV core, PreS/S, and P proteins. Within another embodiment, a coronavirus-derived packaging cell line is provided, comprising an expression cassette which directs the expression of coronavirus N, M, and S proteins.
Within another aspect, a VSV-G derived packaging cell is provided which is suitable for packaging and production of an alphavirus vector, comprising a stably integrated expression cassette which directs the expression of VSV-G. Within a further embodiment, such packaging cell lines comprise a stably integrated expression cassette which directs the expression of one or more alphavirus structural proteins.
Within yet other aspects, producer cell lines are provided based upon the above packaging cell lines. Within one embodiment, such producer cell lines produce recombinant alphavirus particles in response to a differentiation state of the producer cell line. Within other embodiments, such producer cell lines produce recombinant alphavirus particles in response to one or more factors.
As utilized with the context of the present invention, alphavirus producer cell line refers to a cell line which is capable of producing recombinant alphavirus particles. The producer cell line should include an integrated alphavirus structural protein expression cassette capable of directing the expression of alphavirus structural protein(s), and also, an alphavirus vector construct. Preferably, the alphavirus vector construct is a cDNA vector construct. More preferably, the alphavirus vector construct is an integrated cDNA vector construct. When the alphavirus construct is an integrated cDNA vector construct, it may, in some instances, function only in response to one or more factors, or the differentiation state of the alphavirus producer cell line.
In still yet another aspect, the present invention provides alphavirus particles which, upon introduction into a BHK cell, produces an infected cell which is viable at least 24 hours and as much as 48, 72, or 96 hours, or 1 week after infection. Also provided are mammalian cells which contain such alphavirus particles. In addition, recombinant alphavirus particles capable of infecting human cells are provided.
In another aspect, the present invention provides recombinant alphavirus particles which, upon introduction into a BHK cell, produces an infected cell which is viable at least 24 hours after infection, the particle also carrying a vector construct which directs the expression of at least one antigen or modified form thereof in target cells infected with the alphavirus particle, the antigen or modified form thereof being capable of stimulating an immune response within an animal. In various embodiments, the expressed antigen or modified form thereof elicits a cell-mediated immune response, preferably an HLA class I-restricted immune response.
In still another aspect, the present invention provides recombinant alphavirus particles which carry a vector capable of directing the expression of a palliative in cells infected with the alphavirus particle, the palliative being capable of inhibiting a function of a pathogenic agent necessary for pathogenicity. In various embodiments, the pathogenic agent is a virus, fungi, protozoa, or bacteria, and the inhibited function is selected from the group consisting of adsorption, replication, gene expression, assembly, and exit of the pathogenic agent from infected cells. In other embodiments, the pathogenic agent is a cancerous cell, cancer-promoting growth factor, autoimmune disorder, cardiovascular disorders such as restenosis, osteoporosis and male pattern baldness, and the inhibited function selected from the group consisting of cell viability and cell replication. In further embodiments, the vector directs the expression of a toxic palliative in infected target cells in response to the presence in such cells of an entity associated with the pathogenic agent; preferably the palliative is capable of selectively inhibiting the expression of a pathogenic gene or inhibiting the activity of a protein produced by the pathogenic agent. In still further embodiments, the palliative comprises an inhibiting peptide specific for viral protease, an antisense RNA complementary to RNA sequences necessary for pathogenicity, a sense RNA complementary to RNA sequences necessary for pathogenicity, or a defective structural protein of a pathogenic agent, such protein being capable of inhibiting assembly of the pathogenic agent.
In yet further embodiments, recombinant alphavirus particles described above direct the expression of a palliative, more particularly, direct the expression of a gene product capable of activating an otherwise inactive precursor into an active inhibitor of the pathogenic agent, for example, the herpes thymidine kinase gene product, a tumor suppressor gene, or a protein that activates a compound with little or no cytotoxicity into a toxic product in the presence of a pathogenic agent, thereby effecting localized therapy to the pathogenic agent. Alternatively, the recombinant alphavirus particle directs the expression of a protein that is toxic upon processing or modification by a protein derived from a pathogenic agent, a reporting product on the surface of target cells infected with the alphavirus and containing the pathogenic agent, or an RNA molecule which functions as an antisense or ribozyme specific for a pathogenic RNA molecule required for pathogens. In certain embodiments, in the alphavirus particles described above, the protein is herpes thymidine kinase or CD4.
In yet further aspects, the present invention provides recombinant alphavirus particles which direct the expression of a gene capable of suppressing one or more elements of the immune system in target cells infected with the alphavirus vector, and an alphavirus particle which directs the expression of a blocking element in cells infected with the alphavirus vector, the blocking element being capable of binding to either a receptor or an agent such that the receptor/agent interaction is blocked.
In further aspects, methods are provided for administering any of the above-described recombinant alphavirus particles or vectors, for a prophylactic or therapeutic effect. For example, within one aspect, the present invention provides methods of stimulating an immune response to an antigen, comprising the step of infecting susceptible target cells with a recombinant alphavirus particle which directs the expression of at least one antigen or modified form thereof in target cells infected with the alphavirus, the antigen or modified form thereof being capable of stimulating an immune response within an animal. In one embodiment, the target cells are infected in vivo, although within other embodiments the target cells are removed, infected ex vivo, and returned to the animal.
In still further aspects of the present invention, methods of stimulating an immune response to a pathogenic antigen are provided, comprising the step of infecting susceptible target cells with a recombinant alphavirus particle which directs the expression of a modified form of a pathogenic antigen in target cells infected with the alphavirus, the modified antigen being capable of stimulating an immune response within an animal but having reduced pathogenicity relative to the pathogenic antigen.
In even further aspects of the present invention, methods of stimulating an immune response to an antigen are provided, comprising infecting susceptible target cells with a recombinant alphavirus particle which directs the expression of a peptide having multiple epitopes, one or more of the epitopes derived from different proteins.
In yet another aspect of the invention, methods of stimulating an immune response within a warm-blooded animal are provided, comprising infecting susceptible target cells associated with a warm-blooded animal with nucleic acid sequences coding for either individual class I or class II MHC protein, or combinations thereof, and infecting the cells with an alphavirus particle which directs the expression of at least one antigen or modified form thereof in target cells infected with the alphavirus particle, the antigen or modified form thereof being capable of stimulating an immune response within the animal.
In another aspect of the present invention, methods of inhibiting a pathogenic agent are provided, comprising infecting susceptible target cells with an alphavirus particle which directs the expression of a palliative in cells infected with the alphavirus particle, the palliative being capable of inhibiting a function of a pathogenic agent necessary for pathogenicity.
As utilized within the context of the present invention, vector or vector constructs which direct the expression of a heterologous sequence of interest in fact refers to the transcribed vector RNA, which directs the expression of the heterologous sequence of interest. In addition, although xe2x80x9canimalsxe2x80x9d are generally referred to, it should be understood that the present invention may be readily applied to a wide variety of animals (both mammalian and non-mammalian), including for example, humans, chimps, macaques, cows, horses, sheep, dogs, birds, cats, fish, rats, and mice. Further, although alphaviruses such as Sindbis may be specifically described herein, it should be understood that a wide variety of other alphaviruses may also be utilized including, for example, Aura, Venezuelan Equine Encephalitis, Fort Morgan, Ross River, Semliki Forest, and Mayaro.
Within other aspects of the present invention, methods are provided for delivering a heterologous nucleic acid sequence to an animal comprising the steps of administering to the warm-blooded animal a eukaryotic layered vector initiation system as described above. Within certain embodiments, the eukaryotic layered vector initiation system may be introduced into the target cells directly as a DNA molecule by physical means, as a complex with various liposome formulations, or as a DNA-ligand complex including the vector molecule (e.g., along with a polycation compound such as polylysine, a receptor specific ligand, or a psoralen inactivated virus such as Sendai or Adenovirus).
Within yet other aspects of the invention, ex vivo cells are infected with any of the above-described recombinant alphaviruses are provided. Within yet other aspects, recombinant alphavirus particles are provided which are resistant to inactivation in serum. As utilized herein, recombinant alphavirus particles are considered to be resistant to inactivation in serum if the ratio of surviving particles to input/starting particles in a complement inactivation assay is greater in a statistically significant manner, preferably at least 5-fold, and as much as 10- to 20- fold, as compared to a reference sample produced in BHK cells. Within further aspects, pharmaceutical compositions are provided comprising any of the above-described vectors, or recombinant alphavirus particles, in combination with a physiologically acceptable carrier or diluent.
In yet another aspect of the invention, the eukaryotic layered vector initiation systems provided enable new methods for large scale recombinant protein expression.
These and other aspects of the present invention will become evident upon reference to the following detailed description and attached drawings. In addition, various references are set forth below which describe in more detail certain procedures or compositions (e.g, plasmids, etc.). These references are incorporated herein by reference in their entirety.